It is often desirable to collate or otherwise sort the output of machines such as printers, duplicators or photocopiers equipped with sheet-delivering mechanisms. Collating involves placing one copy of each page of a multipage original in separate stacks, each in the same order as that of the original. Automatic collating devices usually are provided with a series of bins, in each of which a complete ordered copy of the original document is deposited. Other forms of sorting may also be desirable. For example, at times, it may be advantageous to automatically stack copies of different original pages, or different numbers of copies of the same original page, in separate bins.
The prior art discloses devices of various types for automatically collating and sorting. Many of them are large and expensive, involving many individual stationary bins in a frame and complicated paper-moving apparatus for altering the path of movement of sheets for directing them as desired to individual bins. Others involve the use of movable trays brought successively to the output station of a sheet-delivering machine, usually with some provision for increasing the spacing between the trays at the output station to facilitate entry therebetween of a delivered sheet. This invention lies within the latter type.
1. Field of the Invention
This invention relates to a sheet-material sorting apparatus of a type wherein movable trays are brought to the output station of a sheet-delivering machine. The trays are individually movable relative to one another for this purpose, and the trays are then movable as a group to reposition them for receipt of the next group of sheets.
2. Description of the Prior Art
One example of a collator of the prior art in which several individual trays are fixed in a frame is that shown in U.S. Pat. No. 3,467,371 to Britt et al. Another general type of prior-art sorting apparatus provides a stack of bins in a frame which moves vertically past the output station of a sheet-feeding device so that successive sheets are placed in successive bins. To save space, some of the prior-art devices use frames or standards for supporting individually movable trays which might be compressed when not in sheet-receiving position and moved apart when in sheet-receiving position. The present invention is of that latter general type. In U.S. Pat. No. 3,788,640 to Stemmle, and U.S. Pat. No. 3,995,748 to Looney, camming devices are used to compress the individually movable bins or trays when they are not in sheet-receiving position. Such camming devices and related apparatus are very complicated, and they inflexibly fix the distance between bins when the bins are compressed. This inflexibility causes problems when a large number of sheets are inserted into any given bin. A similar problem of inflexibility exists with the apparatus disclosed in U.S. Pat. No. 3,721,435 to Zanders, which uses notched belts, rather than cams, to widen and compress the bins. A somewhat different sorting apparatus is disclosed in Xerox Disclosure Journal, page 59 of Volume 1, No. 4, April 1976. Such apparatus has a plurality of trays, each hinged at its rear lower edge. The front edges of all of the trays are tilted up above the sheet-output station and then are allowed to fall one-by-one to below the output station, so that a sheet might be received between the most recently dropped tray and the tray immediately above it. Unfortunately, since the trays of this apparatus are hinged closely together at one end, sheets tend to become pinched if a large number of them are placed between any two trays. Also, the width of the gap between trays at the output station varies greatly as successive trays fall from above to below the output station, decreasing the chance that the sheets will be uniformly placed between different trays.